Is an 'Unknown_Sender!' mms message spam?

I received a message from my daughter. The first two contained photos of my grandchildren. The third said download. I tried to download it and nothing happened. I then record a message that said, 'Unknown_Sender!'

There were no details provided. I tried to block this sender and I then received a message that said messenger has stopped asking with two options.

1. Open the app again
2. Send feedback.

I believe I this is someone who had either hacked my cell or is trying to gain access through my daughter.

Has anyone had this happen? Is it spam? How can I block them or find out if they are illegally hacking me and how do I stop them?

Welcome to Android Central! When you get a text message that says "Tap to Download," that's usually an MMS message that had trouble coming through, often due to a network issue (e.g., if your mobile data connection is poor, or if you forgot to turn on your mobile data in the first place). MMS can be a picture text or a group text. This kind of thing is usually not a hack attempt, so I wouldn't worry about it.